1. Field of the Invention
The present invention relates to a toner supplying device to be detachably mounted into an image forming apparatus, and an image forming apparatus.
2. Description of the Related Art
An image forming apparatus such as a copier or a printer is such that toner is supplied from a developing device toward an electrostatic latent image formed on the outer surface of an image bearing member such as a photoconductive drum to form a toner image corresponding to the electrostatic latent image. This toner image is transferred to a sheet, which is discharged to the outside after a fixing process is applied thereto by heating and pressing in a fixing device.
In such an image forming apparatus, a detachably mountable toner container (toner supplying device) storing a specified amount of toner is attached to the developing device, and an amount of toner corresponding to an amount used for image formation is replenished into the developing device from a container body of this toner container. Normally, the toner container is attached to and detached from the developing device by being slid on a top plate of the developing device in forward and reverse directions. Such a toner container is provided with a toner replenishment opening and a shutter structure for opening and closing the toner replenishment opening at a lower surface side. On the other hand, the developing device is formed with a toner receiving opening at a position corresponding to the toner replenishment opening.
The shutter structure includes a shutter plate in the form of a flat plate which slides in parallel with the container body to open and close the toner replenishment opening by attaching and detaching the toner container to and from the developing device, an elastic arm extending in a sliding direction from one edge portion of the shutter plate and a container locking claw and a developing-device locking claw formed at the leading end of the elastic arm.
On the other hand, a container side engageable portion engageable with and disengageable from the container locking claw is provided near the toner replenishment opening on the toner container and a developing-device side engageable portion engageable with and disengageable from the developing-device locking claw is provided near the toner receiving opening on the developing device.
By linking the engagement and disengagement of the respective locking claws and the respective engageable portions with and from each other, the shutter plate having closed the toner replenishment opening is opened by attaching the toner container to the developing device and the opened toner replenishment opening is closed by the shutter plate by withdrawing the toner container from the developing device. Once the toner container is detached from the developing device, the shutter plate becomes a lock state by engagements of the container locking claw with the container side engageable portion, and will not be opened. Thus, the occurrence of such an inconvenience that the shutter is erroneously opened and the toner inside is leaked from the toner replenishment opening to outside of the toner container can be prevented.
In the conventional toner container provided with such a shutter structure, the container side engageable portion hinders a relative movement of the shutter plate with respect to the toner container in one direction (opposite to an attaching direction of the toner container) with the container locking claw of the shutter plate engaged with the container side engageable portion until the developing-device locking claw is engaged with the developing-device side engageable portion, but permits a movement in other direction at any point of time. In other words, the container side engageable portion is not in the form of a groove, but in the form of a step.
Accordingly, as the toner container once attached to the developing device is withdrawn, the shutter plate moves relative to the toner container since the developing-device locking claw is engaged with the developing device (i.e. the shutter plate does not move relative to the developing device). Thus, when the toner container is detached from the developing device, the shutter plate closes the toner replenishment opening.
However, while the toner container is being withdrawn from the developing device, a relative movement of the shutter plate with respect to the toner container is not hindered until the developing-device locking claw is disengaged from the developing-device side engageable portion. Thus, the shutter plate comes to close the toner replenishment opening. However, since no stopper is provided to hold the closed state by the shutter plate, there is a likelihood that the shutter plate is opened inadvertently by the shutter plate getting caught by something in a state where the toner container is detached from the apparatus body of the image forming apparatus.